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Original Article |
Correspondence to: Yolande Chvatchko, Serono Pharmaceutical Research Institute, 14, chemin des Aulx, 1228 Plan-les-Ouates/Geneva, Switzerland. Tel:41-22-7069-666 Fax:41-22-7069-718 E-mail:yolande.chvatchko{at}serono.com.
CC chemokine receptor (CCR)4, a high affinity receptor for the CC chemokines thymus and activation-regulated chemokine (TARC) and macrophage-derived chemokine (MDC), is expressed in the thymus and spleen, and also by peripheral blood T cells, macrophages, platelets, and basophils. Recent studies have shown that CCR4 is the major chemokine receptor expressed by T helper type 2 (Th2) polarized cells. To study the in vivo role of CCR4, we have generated CCR4-deficient (CCR4-/-) mice by gene targeting. CCR4-/- mice developed normally. Splenocytes and thymocytes isolated from the CCR4-/- mice failed to respond to the CCR4 ligands TARC and MDC, as expected, but also surprisingly did not undergo chemotaxis in vitro in response to macrophage inflammatory protein (MIP)-1
. The CCR4 deletion had no effect on Th2 differentiation in vitro or in a Th2-dependent model of allergic airway inflammation. However, CCR4-/- mice exhibited significantly decreased mortality on administration of high or low dose bacterial lipopolysaccharide (LPS) compared with CCR4+/+ mice. After high dose LPS treatment, serum levels of tumor necrosis factor
, interleukin 1ß, and MIP-1
were reduced in CCR4-/- mice, and decreased expression of MDC and MIP-2 mRNA was detected in peritoneal exudate cells. Analysis of peritoneal lavage cells from CCR4-/- mice by flow cytometry also revealed a significant decrease in the F4/80+ cell population. This may reflect a defect in the ability of the CCR4-/- macrophages to be retained in the peritoneal cavity. Taken together, our data reveal an unexpected role for CCR4 in the inflammatory response leading to LPS-induced lethality.
Key Words: CC chemokine receptor 4, lipopolysaccharide, endotoxic shock, F4/80 antigen, T helper type 2 cells
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